Comparison of steady and unsteady two-phase flow at engine intake valves

A comparison between the steady and unsteady two-phase air/fuel flow through an internal combustion engine intake valve has been studied experimentally in a specially designed rig. The atomisation of liquid fuel film flows around the valve gap and its subsequent impingement onto the neighbouring walls can readily be seen. Similarities in the flow patterns between steady and unsteady modes of valve and injector operation are also apparent. The effects of altering the injection timing for the unsteady case shows that injection prior to valve opening yields a considerable increase of fuel impingement within the chamber beneath the valve. A brief description of the base airflow is also given alongside the two-phase data.